Line tracing mechanism



Nov; 23, 1943. D, HOW LL 2,334,824

LINE TRAGING MECHANISM Filed July 9, 1941 2 Sheets-Sheet 1 INVENTOR JOHN D. HOWELL Y ATTORN EY Nov. 23, 1943. J. D. HOWELL. 2,334,824

LINE TRACING- MECHANiSM Filed July 9, 1941 v 2 Sheets-Sheet 2 H W V .25

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INVENTOR X/% JOHN D. HOWELL ATTORNEY Patented Nov. 23, 19.43

rm raaomo MECHANISM John D. Howell, Ilion, N. Y., assignor,;by mesne. assignments, to UnionCarbide and Carbon G015. poration, ac'oi'poration of New York 7v J I Application a t, IS ILiS erial No. 4 01,61-6

s claim (circa-23 This invention relates to propelling apparatus and more particularly to a driving unit or tracing head employed in connection with shape-cutting machines. t

It is common practice to mounta cutting blowpipe or similar too-1 upon a supporting. carriage for movement in varying directionsover a work surface, to reproduce a predetermined contour. A reproducing machine of this type adapted to propel a blowpipe in varying directions is fully disclosed in U. S. Patent to S, R. Oldham; No.

2,279,338 dated April 14, 1942. It is customary with such machines to employ a driving' unit which tractionally engages a paper or similar templet mounted on a supporting surface, which driving unit maybe guided manually along the prescribed course so as toimpart corresponding motion to the blowpipeor other tool.

'Since the motion imparted to the carriage is governed by the motion of the axis of the pivotable driving unit or tracinghead, it is customary to locate the tracing wlieel centrally, so as to engage the templet path at a point coincident with the axis of the tracing head. has offered substantial disadvantages in operation because'the tracing wheel obscures the line drawn on the paper templet during the entire tracing operation, thereby increasing the personal error in the motion of the reproducing tool during hand-guided tracing operations. Furthermore headaxis to follow the contour line; and to provide an improved tracing headwherein the .trac

. tio'n wheelatall times revolves ireely in an orbit therepeated passage of the tracing wheel over the templet contour effaces the line or path drawn on the templet, thereby involvingcexpensive maintenance work on the part of skilled draftsmen to'keep the templets in useful condition. Also, since it iscustomary to serrate or knurl the periphery of the tracing Wheel to obtain better traction, th 'templet issubjected to abusive treatment each time the wheeljtraces the contour, so that'in a short time the paper is completely worn through. The abrasion: is

more noticeable atsharp corners because of the scraping and twisting action on the templet whenever the wheel is turned abruptly about the point of rolling contact. r

are: to provide a driving unit for-shape cutting machines, and the like, which unit overcomes the prior 'art'defects enumerated-in the preceding paragraph; to provide an improved tracing head which renders the contourline of the templet The principal objects of the present invention wheel'unit 1 2 0 U l takenon the line 5-5 of Fig. 3; and,

about theaxi s of the head. 'These and other ob- :"J'ects of the present invention will become apparent from the following description 'andtfroin the accompanying drawings disclosing one form fof the improved tracing head "as applied to a shapecutting machine of the type disclosed in S. R.v Oldharh Patent No. 2279,3313; In the drawings:

' Fig. 1 comprises averticalcrossfsectional View through the improved tracing head, shownattached to the'carriage'of a reproducing machine; Fig. 2 is a vertical sectional View of the tracing,- wheel unit,*taken*on the line 2-2of Fig. 3;

Figf3 is a pl'a'n View of the tracing-wheeljunit; Fig. 41s a side elevational view of the'tra'cing- Fig. 5. is a sectional View through'the gearing,

7 'Fig. 6 is a" diagrammatic vie er {the entire gearing'system employed in the new tracing head.

Generally speakinggthe invention comprises" a pivotablehand-"guided tracing head H adapted to be connected to the universally-movable car'- ria'ge C'of a-sliape-cutting or similar. contouring machine. A "traction Wheel W, which is oifst laterally from the head axis, engages a templet T mounted on 1 asuitable supporting surface.

Kmotor (not shown) mounted on'tlie carriage C provides motive'power for the wheel W, the motion being "transmitted througha variablespeed transmission V (controlled by a speed adjuster A),- and through gearing-G.

"The headH comprises a housing I l of gener lly cylindricalshapejournalled to a depending portion'. [2 of the'carriage C for rotation about a r central'axis X. The headI-I is urged downwardly intooperative engagement with the templet T by means of compression spring [3 acting through a'thru'st bearing [4. Spokes l5'project-- ing radially from the housing I I serve as a handle to assist the operator in manually pivoting the housing-l f, and thereby the entirehead I-I, so as to control thedirection oftravel of the whee1W.- The' central axis X of thehead H is maintained substantially normal to the operating surface 1 on-which'the templet T'is supported. "Ordivisible to the operator at all times; to provide] an improved tracing head having a tracing wheel which at no time-rolls along the; contour line of the templet, but yet which allowsthe tracing 'n'arily the templet -'1 is maintained in! a horizontai plane and the head H pivots about a vertical axis to impart motion to the carriage C in varying directions in' a' horizontal plane. Auxiliarysteeringmeans comprising a gear It cooperative; with teeth "on the'headH permit pivots about its axis, the planetary pinions revolve in an orbit aboutthe periphery of the sun Shafts 23 and 24' extend pinions I8 and I9. downwardly from the planetary pinions and are provided with flattened portions attheir lower end for detachable connection with interchange- V able traction-propelling units such as a tracing-- wheel unit 20, shown in Fig. 2: :The shafts; 23- and 24 may engage a pair of spaced trunnions adapted to roll along opposite edges of a raised templet strip, as shown in svR. Oldham Patent No. 2,279,338.- With a hand-guided propelling unit. having-a tractionwheelW, as-shown in Figs. v

2:and4 ;,only-a sing le drivingconnection is necessary.. Since both pinions I8and I!) are; positively rota-tedrelatively to. the head H, connection to the traction; wheel W may be. made. from. either pinion. As shown. in Fig. l ,-the gearing G, employed totransmitpower from the driving pinion to thewheel: W, operatively. connects with the sun pinion I9. 7

ime tracing-wheel unitztl. disclosedinFigs; 2, 3, and:4comprises-agenerally cylindrical mounting, detaehably 'conneoted,..asby .a. screw 25, within the" lower end ofthev headI-I. The unit 20 comprisesa housing: Z-E WhlCh fOImS'a natural extension of the housing H when-the parts are assembled- 'L'hetractioni wheeL -W is journalled to the housing 26 as by a bearing 2-1 rotatable upona preferably horizontal spindle-28g Asbest seen in Fig-.6; the wheel W.,. having an: effective radius R,- engages the templet T at at point spaced transversely from the'ax-is' of the head the point of-rolling' contact beingofiset laterally from wheel W about spindle 28 as the radius of the wheel W is related to the distance E. This same relationship may be established in equation form The gearingGincludesa geartrain 32, mounted within the housing'2 '6 for connection with the shaft '24 through a coupling 33, pinned to the top end of a shaft 34. The central aperture at the top of coupling 33 is splined or fiattened to enter into locking engagement with a similarly shaped portion on the bottom of the shaft 24 whenever the unit slides within the housing Hr Speed reduction from the shaft 24 is ob- 'theaxis by'the distance E, Accordingly, as the eithersidezof the contour line; thereby producing no: wear on: the line itself. This arrangement 7 provides two.- paths. alongi'wh-ich the wheel may Troll, thereby-doubling the useful. life. of the templets. I Q r 1 Asthe housing rotates, the wheel: W is free to .roli in an orbit; relatively to. the driving mechan'ism or inion [9. ,This action-his obtained by selectingv gearing G having such a speed ratio between the driving pin-ion l9 and the wheel W, thatasthe housing-H pivots so as to cause the pinion 22 to revolve in arr, orbitabout the .pe-

.ripheryof the sun pinion l'9, the wheel Wfrol-ls freely in its own orbit about the axis X without slilflpegeonthe templet T.- .With a gear arrange .ment'as disclosed in Fig. 6, the necessary relaq-tionshipxto produce this result is obtained when the speed of gear I9 is related to the speed of tained through gears 35, 36, and 31, which drive a gear 38 and a bevel pinion 39, both of which are journalled as a unit on shaft 34 for rotary. movement with respect thereto. The motion of.

pinion" 39 is transmitted to a bevel gear 41 formed integrally with-or otherwise secured to the wheel Any similar arrangement of transmission engagement with a fixed axial driving member;

such as pinion I'9. If the pivoting action occurs while-the driving pinion is positively rotated, the total angular velocity ofthe; traction-wheebrep resents the'algebraic' sum of the normal, driving velocity and the increment produced jby the planetary action during pivoting of the hea'd.

This increment compensates for'the larger an'd smaller path respectively required to be followed by the wheel in tracing outside and inside curves, and maintains the traversing velocity of the pointerconstant.

Various modifications of the herein disclosed invention may be made without departing"from,

the principles oi the invention .or'sacrificing its advantages. I j I claim:

1'. A drivingunit for shape-cutting machine s,

and the like, saidv unit being adapted ,to be man.- ually guided in varying directions. over ,a-iprerscribed course located on a supporting su'rface,

said unit comprising a housing. manually' pivot.- able about. an axis. substantially normal to said surface; a. traction wheel journalled to the lower partof saidhousing for driving engagement with Saidsurface at a point spaced transversely from .said axis; a. positively driven sun pinion coaxially mounted within the upper part of said housing; .a planetary pinion in engagementwith and re.- volvable about said sun-pinion as said housing pivots; and transmission means extendingfrom said upper part to said lower .part of saidahous n for connecting said planetary pinion and said traction wheel.

I 'Propellinga paratus for contouringma-- chines, and the like, adapted to be manually guided about a predetermined course .on a supporting surface, said apparatus comprising a housing manually pivotable about an axis extending perpendicularly to said surface; a driving pinion located on said axis; a tractionwheel journalled to. said housing for rolling engage,-

Y ment with said surface at a' point spaced trans.-

versely from: said axis; and gearing voperatively connecting, said driving pinion and said traction wheel, said gearing including a-planetary pinion rotatably mounted in said housing on an'axis parallel to and .spaced from said housing-axis and thereby adapted when said housing pivots to roll freely about the periphery of said driving pinion through an angle, and to provide free rolling movement of said traction wheel about its orbit through an equal angle.

3. In an axially pivotable tracing head, for

shape-cutting machines, and the like, adapted for manual guidance about a predetermined course on a supporting surface, the combination free to roll in an orbit'about said axis relatively to said driving mechanism; said driving mechanism including an axial drive shaft and a countershaft parallel with said drive shaft and re volvable about said drive shaft; through an angle equal to the angle through which saidwheel rolls in its orbit.

4. A tracing head adapted to impart movement to a blowpipe-supporting carriage, or the like, in varying directions in a horizontal. plane in accordance with a prescribed path located on a horizontal supporting surface, said head comprising a manually pivotable housing adapted to be connected to such carriage for pivotal movement about a vertical axis; a single traction wheel journalled to the lower end of said housing within said housing on an axis spaced from and about a generally horizontal axis, said wheel being adapted to engage said surface tractionally to impart movement to said head in a direction governed by the pivotal position of said housing, the point of 'tractionalengagernent"of said wheel being spaced transversely from said vertical axis; a driving pinion rotatably mounted in the upper part of said housing; a driven pinion rotatably mounted in the upper part of said housing on an axis spaced from the housing axis; transmission means extending from said driven pinion to said traction wheel; and. a pointer depending from said housing toward said surface coincident with said housing axis and,

thereby clearly visible from the axis side of said traction wheel.

5. In a tracing head, manually pivotable about a central-axis with respect to a supporting surface, the combination comprising a driving pinion rotatable with respect to said head on said.

an axis substantially normal to said surface; a

driving. member coaxially mounted within said housing; a traction wheel rotatably supported by said housing for driving engagement with said surface at alpoint spaced from said axis; and transmission mechanism operatively connecting said member and said traction wheel, said trans mission mechanism having a speed ratio equal to the ratio between the radiusof said traction wheel and the distance separating said point from said axis. i v

7. A tracing head adapted to impart movement to a blowpipe-supporting carriage, or the like, invarying directions in a horizontal plane in accordance with a prescribed path located on a horizontal supporting surface, said head comprising a manually pivotable housing of generally cylindrical shape adapted to be journalled about a central vertical axis to said carriage; a vertical driving pinion extending within said housing at the top thereof in alignment with said axis; gearing including a planetary pinion journalled parallel to said central vertical axis for operative engagement with said driving pinion, said planetary pinion thereby being revolvable in an orbit about said driving pinion as said housing pivots; and a traction wheel driven by said gearing, said wheel being journalled to the lower end of said housing about'a generally horizontal axis said wheel being adapted to engage said surface tractionally to impart movement to said head in a -direction governed by the pivotal position of said housing, the point of tractional engagement of said wheel with said surface being spaced laterally from said central vertical axis sufficiently that said traction wheel freely rolls in an orbital path about said vertical axis through the same arc as said planetary pinion revolves about said driving pinion when said housing pivots. V

8. A manually-guidable tracing head for a shape-cutting or similar machine adapted to impart movement in varying directions in a horizontal plane to a tool-supporting carriage in accordance with a predetermined contour defined ona horizontal supporting surface, said head comprising a manually pivotal housing connected to said carriage for pivotal movement central axis; a traction wheel ofiset laterally 7 from said central axis and being revolvable in an orbit with said head about said central axis; and gearing including a planetary pinion engageable with and revolvable about the'periphery of said driving pinion, said gearing operatively connecting said pinion and said wheel with a speed ratio equal to the ratio between the diameter of said wheel and the diameterof said orbit. f

6. 'A' tracing head adapted to be manually guided in varying directions over a prescribed course located on a supporting surface, said head' Y about avertical axis; a driving pinion coaxial with said head; a traction wheel adapted to engage said surface and to roll along said contour in response topivoting guidingmotion of said head, said wheel being spaced from said axis and comprising a housing manually pivotable about beingfree to roll about an orbit having a'radius equal to such spacing at the point of rolling con tact; and positive planetary gear mechanism between said axial pinion and said wheel having a gear ratio adapted, when said housing is pivotecl so as to rotate said mechanism through any angle about said pinion while said pinion is stationary, to impart positive rolling motion to said traction wheel about its orbit through an equal angle. w

JOHN D. HOWELL. 

